Ionic discharge tube



y 1936- T. J. KILLIAN IONIC DISCHARGE TUBE Filed May 8, 1955 mm J v mUh- /.V a M 5 VI E N R O T T Patented May 19, 1936 PATENT," OFFICE IONICDISCHARGE TUBE Thomas J. Killian, Seattle, Wash, assignor to LuminousTube Lighting Corporation, Seattle,

Wash, a corporation Application May 8,1933, Serial No. 670,008

2 Claims. (61. 176-125) The present invention relates to gaseousdischarge devices and more particularly to devices of the charactergenerally known as luminous I gaseous discharge tubes.

One of the objects of this invention is to provide a luminous dischargetube or lamp of such a character that the desired initial quality,quantity and efficiency of light produced will remain practicallyunchanged over long periods of operation of the tube.

Another object of the invention is to provide a gaseous discharge tubeor lamp of such a character that the operating efficiency will bemaintained substantially unchanged over a long period of time by keepingsubstantially constant not only the total pressure of the mixture ofgases in the discharge tube, but also their partial pressures.

In order that a luminous gas discharge tube using chemically activegases such as carbon dioxide, carbon'monoxide, nitrogen, etc., or usingmixtures including one or more of these gases, may have a long lifeduring which the quantity, quality and efliciency of light remainpractically 25, unchanged, it is necessary that not only the totalpressure but also the partial pressures of the constituent gases remain,unchanged. While it has been known for many years that carbon dioxideor monoxide will give a fine white light,-

similar to north sky light, due to a very densely filled and wellbalanced spectrum, I have found that in order to produce this light overlong periods of time, it is necessary to maintain the equilibrium of themixture of carbon dioxide, carbon monoxide, oxygen and varioussub-oxides of carbon into which carbon dioxide or monoxide breaks upwhen ionized.

In any gas filled discharge tube there is a. gradual disappearance ofgas which is called "clean up and it has been found that in this cleanup various gases disappear at diiierent rates. I have found that anexcess of oxygen lowers the efiiciency of the tube more than any otherconstituent gas and also in a tube using dielectric or condenserelectrodes and carbon dioxide that oxygen cleans up more slowly thanother gases. Therefore it is impossible to obtain long life and maintainefficiency of atube by merely renewing or supplementing the supply ofcarbon dioxide since, in so doing, the equilibrium of the mixture isgradually changed and the efilciency of the tube is steadily decreased.

It has been found that in the operation of gaseous discharge lamps,using carbon dioxide, carbon monoxide or other active gases, they willordinarily change rather rapidly in efiiciency and quality of the lightproduced. This invention makes it possible to maintain the initialefliciency and quality of light produced over long periods of time,exceeding a thousand hours.

By this invention means are provided whereby large and bulky lamps mayalso be conditioned for use in a simplified manner.

In carrying out this invention an activator, preferably in the form ofporous or finely divided material or material whose area is largecompared to its volume, is placed in direct contact with the gas in anionic discharge tube. Such discharge tubes may be easily and quicklyreconditioned in accordance with this invention and proper conditioningof large and bulky lamps of this sort can be effected without employinga baking out treatment.

Other objects and advantages of the invention will be apparent duringthe course of the following detailed description, taken in connectionwith the accompanying drawing, forming a partof this specification andin which drawing:

Figure 1 is a somewhat diagrammatic view showing the preferredembodiment of the invention, together with the electrical circuit;Figures 2 and 3 are slightly enlarged views of one of the electrodes onthe corresponding respective lines shown in Figure 1; and Figure 4 is adetail sectional view through two of the electrode tubes on an enlargedscale.

In the drawing and wherein similar reference characters designatecorresponding parts throughout the several views, the letter Adesignates the body portion or luminous portion of a gaseous or ionicdischarge tube, provided at each end with a dielectric electrode B. Atransformer C is indicated having electrical connection with theelectrodes B. Means D is shown for maintaining the equilibrium of thegaseous mixture in the tube section.

The tube A may be of any suitable material, size or shape in accordancewith the particular use for which the lamp is intended and may be madefrom any clear glass that is not easily cracked or broken.

The electrodes B may be formed of any suitable glass capable ofwithstanding ordinary strains encountered in apparatus of thischaracter. Each electrode B comprises a main header 5 sealed to the tubeA. A series of preferably L-shaped carrier tubes or headers 6,preferably of less diameter than the main header tube 5, is connected inparallel spaced-apart relation along the length of the header I toproject in right angular relation thereto. A series or group ofelectrode tubes or tips I, which may be of less diameter than the header6 and extend in parallel spaced-apart relation to one another and to thevertical or long leg of the header, is connected to the short orhorizontal leg of each header 6. These groups of tubes or tips I arearranged in parallel planes whereby vertical air spaces are providedbetween the tubes.

A coating 8 of conducting material, as shown in Figure 4, is appliedover the entire or any suitably large portion of the electrodes, and asuitable lacquer 9 may be applied over this materialto insulate the sameand minimize static discharge. A terminal wire l0 which is rigidlyembedded in the conducting material and lacquer covering is looped aboutthe headers 6 prior to application of the coating 8 to the electrodes.These terminal wires have one end exposed for making connections withthe secondary terminals of the transformer C.

The transformer C may be of any suitable type and in the example shownembodies a frame H provided with a primary winding l2 supplied by asource of alternating current I3 ofordinary commercial frequency, and asecondary winding l4 connected by conductors I5 to the terminal wires IDof the electrodes. Arranged between the windings l2 and. I4 are ironcross pieces l6 which serve to provide the proper amount of leakage ofmagnetic flux and compensate for the capacitance of the dielectricelectrodes, so that the power factor may be kept as near unity as isdesired. The means indicated at D consists broadly of a device foreffecting contact between a properly conditioned porous material or afinely divided material or substance whose area is large compared to itsvolume and the gas in the discharge tube, thus preserving not only thetotal pressure of amixture of gases in the tube constant, but also theirpartial pressures.

This is done in the present embodiment of the invention by placingfinely divided or porous material, as indicated at 20, in a small glassappendix or the like connected to the discharge tube at any suitablepoint and preferably adjacent one of the electrodes. In the exampleillustrated, this appendix embodies a bulb-like container portion 2|having a small neck or tube 22 which is connected to the discharge tube.One or any other desired number of these appendixes may be connected tothe discharge tube at convenient places, such as the ends orintermediate portions. While the finely divided or porous material 20 ispreferably placed in an appendix for connection to the discharge tube,the material may be placed in suitable quantities in either the headers6 or tips I or the tube A, if desired.

The material 20 may be conditioned before it is placed in the appendixin such a way that it will adsorb or absorb large quantities of gas ormixture of gases. The conditioning of the finely divided or porousmaterial may be effected by heating the same to drive oft undesirablevapors or gases, leaving the same in a condition to readily adsorb orabsorb the desired gas or gases. How-- ever, it has been found in somecases that charcoal, for example, can be used without any specialconditioning. The desired gas or gases may be adsorbed or absorbed bythe fin'ely divided or porous material either before or after it isplaced in the appendix or before or after the appendix containing it isattached to a lamp tube, simply by bringing the gas into contact withthe material.

In operation of the ionic discharge tube embodying this invention; thereis a constant exchange of molecules between the gaseous and the absorbedor adsorbed phases whereby the gaseous when there are small quantitiesof water vapor or other impurities in the discharge tube which wouldaflect its efficiency, they will be taken up by the material in theappendix after several minutes of running the tube, and will onlyslightly dilute the gas absorbed or adsorbed in it.

In a comparison test two lamps or discharge tubes consisting oftwenty-three feet of 11 mm. tubing with dielectric electrodes similar tothose described herein were given identical treatments with theexception that one lamp was provided with an appendix as describedherein containing about two or three cubic centimeters of willowcharcoal. Each lamp was evacuated and baked for several hours at 300 to350. C. and was al lowed to remain over night filled with an atmosphereof carbon dioxide. The pressure was then reduced to about 0.2 mm. andthe lamps were sealed off. Current was then applied to the lamps and thelamp without the appendix showed signs of decline in fifteen hours ofrunning and went out at the end of approximately twenty-five hours. Thepressure in it had dropped to less than 0.02 mm. The other lamp whichwas provided with the appendix containing charcoal, ran four hundredhours with no apparent change, and when the pressure in this lampapparently began to drop the bulb 20 of the appendix was gently heatedwith a small flame and the lamp ran nine hundred additional hours withno perceptible change in efliciency or in quality of light. This heatingof the appendix apparently liberated some 'of the adsorbed gas in thecharcoal and increased the rate of transfer of molecules between phases.

If a lamp has been sealed off at too high a pressure, cooling theappendix with carbon dioxide snow or liquid air will give the lamp itsdesired characteristics.

By other methods, but similar to those previously stated, ofconditioning the material 20, lamps have been produced whichcontinuously carried electric current of thirty milliamperes and overfor more than a thousand hours with a change of any observable variableof less than ten per cent.

The activator 20 of finely divided or porous material may be willowcharcoal, lamp black, bone black, activated carbon, platinum black,powdered glass, powdered ceramic materials, etc. The activator materialmayalso be in the form of needles, flakes, etc. Although the activatormay be used inside of the lamp proper, and has been so used, there aremany advantages in having such activating material in an appendix suchas D connected to the lamp. Among these advantages are that largenumbers of the appendixes can be prepared and conditioned at one timeand sealed oif until required; the appendix is not subjected to thevariations in temperature which the lamp proper undergoes; the inside ofthe lamp is keptvfree of any foreign substance likely to impair itsefilciency, and lamps the appendix.

In the production of luminous discharge tubes which are too bulky to bebaked out, the removal of impurities is a long and tedious processinvolving numerous rinsings, pumpings and running of the lamps and thisprocess in some instances requires several days or even weeks. By thisinvention the conditioning of large and bulky discharge tubes may begreatly expedited. For example, a discharge tube lamp which was toobulky to be baked out was conditioned by attaching appendixes similar tothat described herein to each electrode of the lamp, pumping the lampout, gently heating the activated material, then filling the lamp toatmospheric pressure with carbon dioxide and after several hoursevacuating it to about 0.2 mm. of mercury. An electric current was thenapplied to the lamp and at first the lamp was quite pink due to watervapor. After running the lamp for a few minutes, this color haddisappeared and shortly thereafter the water vapor could not even bedetected spectroscopically and the lamp ran unchanged many hundreds ofhours. Other lamps which were similarly treated have run as eflicientlyas those lamps which have had the best baking-out vacuum treatment.

Numerous tests that have been conducted indicate that the maintenance ofpressure and composition of the gases in the lamp system by thisinvention is not confined to the chemically active gases mentionedabove, but is also practicable with all gases and mixtures of gaseswhich are comparatively stable under the action of electricaldischarges.

I claim:

1. The process of producing a gaseous discharge lamp which comprisespumping out the lamp, placing an activator that has been conditionedwith adsorbed gas in communication with the interior of the lamp, gentlyheating the activator, filling the lamp to atmospheric pressure withcarbon dioxide and after several hours evacuating the lamp to thedesired pressure, then applying an operating current to the lamp, andmaintaining communication between the interior of said lamp and saidactivator during normal operation of said lamp.

2. The process which comprises introducing oxides of carbon into a tubefor luminous purposes, bringing carbon with adsorbed carbon dioxide intocontact with said gases, sealing ofi said tube at a. pressure higherthan necessary for luminous purposes and reducing the pressure bycooling said carbon.

THOMAS J.

